Conventionally, there have been troubles finding out how to keep valuables such as wallets, cell-phones, IDs during outdoor leisure activities. For example, there is no choice but to climb a mountain or swim in sea with leaving valuables at a base point when it is trouble to carry with the valuables. In such a case, members take turns in watching their valuables, diminishing pleasant time with all members. Japanese published patent application No. H08-10022 discloses a waterproof carrying pouch for valuables, but some troubles such as blocking movements are inevitable despite its compactness as long as it is used with being carried on you.
To that end, Japanese published patent application No. 2004-129706 discloses a portable storage body for storing valuables and heavy goods having an opening part with a lid. The storage body stores sea water, sand, and stones as heavy goods when used with a view to preventing theft by making the storage body hard to be carried away.
However, the portable storage body of Japanese published patent application No. 2004-129706 has some problems: necessity of a key being kept with a user at least because the lid and the storage body are connected and locked by means of a commonly-used manual key, possibility of being unable to unlock due to loss of the key, and lack of countermeasure against carrying away in spite of the body's heavy weight.
In view of the above-explained problems in related art, it is an objective of the present invention to provide a safety box which is easy to carry when not in use. In addition, considerable weight can be added to the safety box when used, an operation of locking/unlocking is easy without any possibility of loss of the key, and a countermeasure against carrying away is provided in the safety box.